cancel
Showing results for 
Search instead for 
Did you mean: 
cancel
Showing results for 
Search instead for 
Did you mean: 

Center of Gravity

ptc-1868133
1-Newbie

Center of Gravity

Is there a way to create a feature at the center of gravity when using the mass analysis tool? I would like to be able to reference the center of gravity on a drawing without manually creating a feature or sketch that I can measure to.

WF3.0 M130


This thread is inactive and closed by the PTC Community Management Team. If you would like to provide a reply and re-open this thread, please notify the moderator and reference the thread. You may also use "Start a topic" button to ask a new question. Please be sure to include what version of the PTC product you are using so another community member knowledgeable about your version may be able to assist.
10 REPLIES 10

Tim,

If you have Behavioral Modeler (BMX) all that's required is to run a Mass Properties analysis and save it as a feature. Once you've defined it as a feature instead of quick, or saved you can access the CSYS_COG and PNT_COG options to create either a coordinate system or point at the center of gravity. If you don't have BMX I believe you're stuck with a manual process. Buy BMX, its great!

Regards,






Robert Pomarico
Application Engineer, TriStar, Inc.

From the responses I have received, I learned that it is possible to create a datum point or a coordinate system at the CG of a part or assembly IF you have the behavioral modeling extension. I don't have the extension, so I will stick to creating a point manually. Thanks for the responses.

Tim, You have been misled. When in the Mass-props dialog box you will
notice a pulldown at the bottom set to quick. Select feature, then also
select the feature tab at the top. You should then be able to select the
"pnt_cog" in the datums box and click done.

This will create a point at the Center of Gravity as a feature that you
can select.






Tim Jabaay wrote:
> >From the responses I have received, I learned that it is possible to
> create a datum point or a coordinate system at the CG of a part or
> assembly *IF* you have the behavioral modeling extension. I don't have
> the extension, so I will stick to creating a point manually. Thanks for
> the responses.
>
>
> -----End Original Message-----

Scott,

Thanks for clearing that up. Analysis Features were pulled out of the
Behavioral Modeling extension back in WF2.0 for this very reason and are
available with Foundation XE.

BMX is still the best choice for running sensitivity, feasibility and
optimization studies as well as complex design of experiments
simulations. I personally use BMX any time I know the measurement I
want to meet but can't (or don't want) to change my dimensioning scheme
to directly drive it. It's great at capturing and enforcing a
requirement to meet a certain length, area, volume, clearance, etc.

Happy modeling,


Kevin Schoonover
PTC Channel Technical Manager
Western North America

OK,



I tried this, but the CSYS_COG and PNT_COG options are grayed out. ...






Make sure you have selected the analysis type as a feature instead of quick. I not sure if that is independent of BMX or not though.

Hi,



Sorry for not putting a summary together for this earlier, the BMX option is
required to do this.



Thanks again to Lyle for sending me this workaround.



They add a coordinate system origin, and give it these relations

$d =mp_cg_x(","ACS0",")

$d =mp_cg_y(","ACS0",")

$d =mp_cg_z(","ACS0",")



Where ACS0 is the default assembly coordinate system, and we just put in the
appropriate dimensions in there at $d.





Best regards

Stephen



All,

In an earlier post I misspoke. I mentioned that one could create
analysis features without BMX and that is correct; however, those
features will NOT create geometry (like a point or csys) without BMX,
but they will capture the measurements as parameters. Sorry for the
confusion.

To use those parameters in relations, use the syntax
"$d?=parameter:fid_featurename." As an example, if an analysis feature
is named "MEASURE" and it creates a parameter called "DISTANCE", then a
relation using it might be "$d15=DISTANCE:fid_MEASURE" Be sure to
include the "$" before the dimension to allow negative values to be set.
Also be aware that a double regeneration is often required when using
relations in this way.

Thanks also to Stephen for pointing out the "mp_" equations as an
alternative to using analysis features for mass property calcs.

Regards,

Kevin



Kevin Schoonover
PTC Channel Technical Manager
Western North America

Back in the day; someone who was endowed with BMX could bake an
analysis feature, inclusive of an embedded datum csys/point, into a UDF
(e.g. a *.gph file) to share with a colleague who wasn't so fortunate.
The party with the BMX-less license could then read that UDF into the
target model where the resulting feature was fully functional. Forward
thinking individuals even moved those types of analysis features into the
footer of the model tree and/or amended them to their templates (e.g.
"start parts") ...

I haven't tried that technique in quite some time but it may still work.


Regards,

Dustin Neifer
General Dynamics Land Systems







"Schoonover, Kevin" <->
05/20/2008 12:14 PM
Please respond to
"Schoonover, Kevin" <->


To
Stephen Whyte <->,
-
cc

Subject
[proecad] - RE: Centre of Gravity






All,

In an earlier post I misspoke. I mentioned that one could create analysis
features without BMX and that is correct; however, those features will NOT
create geometry (like a point or csys) without BMX, but they will capture
the measurements as parameters. Sorry for the confusion.

To use those parameters in relations, use the syntax
"$d?=parameter:fid_featurename." As an example, if an analysis feature is
named "MEASURE" and it creates a parameter called "DISTANCE", then a
relation using it might be "$d15=DISTANCE:fid_MEASURE" Be sure to include
the "$" before the dimension to allow negative values to be set. Also be
aware that a double regeneration is often required when using relations in
this way.

Thanks also to Stephen for pointing out the "mp_" equations as an
alternative to using analysis features for mass property calcs.

Regards,

Kevin



Kevin Schoonover
PTC Channel Technical Manager
Western North America

I was looking for the Mass Properties dialog box you mentioned. I went to Assem Setup, Mass Props and picked that.


I get the Setup Mass Properties box but there is no pulldown at the bottom.


Am I looking in the wrong place?

Announcements